Manufacture of threads from viscose



Jan. 18, 1938. w. ZETZSCHE ET .AL 2,105,852

MANUFACTURE OF THREADS FROM VISGOSE Filed June 18, 1936 Watt/2e?" Zetzsche Eric/L Graumann- Inventors By Their Afforneys I tank $01 QLM Patented Jan. 18, 1938 UNITED STATES PATENT OFFICE Walther Zetzsche and Erich Graumann, Premnitz, Germany, assignors to I. G. Farbenindustrie Aktiengesellschaft, Frankfort-on-the- Main, Germany Application June 18, 1936, Serial No. 85,907 In Germany June 27, 1935 Claims.

Our present invention relates to the manufacture of threads from viscose.

One of its objects is a process of producing threads from viscose cut into staples and having 5 an improved curliness as compared with those hitherto known. Further objects will be seen from thedetailed specification following hereafter.

A known process of imparting curliness to freshly spun threads of cellulose hydrate or cellulose ester consists in passing them between fluted rollers or by subjecting them to some other mechanical operation. When this known process is applied in the manufacture of viscose threads the operation must be applied to the fibers in a bath suitable for decomposing the viscose to produce cellulose hydrate or after the use of such a bath. It has been found that as the activity of the bath diminishes or as the kind of viscose used varies, and according to the point of time at which the rollers or like devices act upon the threads, different results are obtained; the kind and the strength of the curliness produced in the thread by the process are more or less accidental and not in accordance with any rule.

This invention relates to a process of this kind which can yield very constant results if the operation of precipitating the viscose is divided into two sections, namely a coagulation of the cellulose xanthate and decomposition of the latter into cellulose hydrate, and the mechanical operation for imparting curliness is applied to the fiber after the coagulation of the cellulose xanthate and before the decomposition into cellulose hydrate.

Thus the threads issuing from the nozzle are first treated with a bath which has only a precipitating action without decomposing the cellulose xanthate. Such a bath may contain, for

example, as the precipitating agent, an organic acid, ammonium sulfate or sodium sulfate or a mixture of these salts, without acid or in the presence of a very small proportion of acid. After the threads have issued from the coagulation bath they are subjected to the action of the known devices for creasing and crimping the threads while they are travelling. For example, the threads may be crimped between fluted rollers or between a fluted roller and a yielding bed.

Only after the threads have left the crimping device are they subjected to decomposition to cellulose hydrate. This decomposition can be brought about in known manner by chemical agents, for example by the known spinning bath or by a solution of a mineral acid or by a physical operation, for example by heating to a high temperature, which is not in itself an agent for decomposing cellulose xanthate.

Reference is made to the accompanying drawing which is a sectional view of the apparatus 5 used in our process. After the threads have issued from the coagulating bath, they are led over a series of rollers I, then are crimped between fiuted rollers 2. Then the threads are cut into staples by a cutting machine 3 and are 10 passed from there over an endless band 4 into a decomposition trough 5.

By this process there is produced, under all conditions, a satisfactory crimped or curled thread, which is very uniform and has a very l5 good staple, as a substitute for W001. The staple cutting machine, preferably follows directly on the crimping device and is followed by the decomposing bath. In this case the xanthate threads are passed through the crimping device 20 to the cutting machine. The cellulose hydrate threads are finally decomposed, preferably in a trough in which they float, or by being sprinkled on an endless permeable band which follows the cutting machine. Since the fibers are free to 25 shrink in cut condition the curliness is improved by decomposing the xanthate in the staple form, particularly as this decomposition is produced by the high temperature of the liquid bath and not by the chemical composition of the bath.

However, the bath for decomposing the xanthate threads need not necessarily be brought into action on the cut sliver, in which case the cutting machine may follow the decomposing bath.

The viscose from ripened alkali cellulose, with a content of 7 to 8 percent of cellulose and 5.5 to 7 per cent of alkali, is spun, preferably at a ripeness corresponding with a salt number of 5 to 7, through metal nozzles having 600 to 1200 40 perforations of suitable diameter, for example 0.08 mm., into a coagulation bath comprising 15 to 25 per cent of ammonium sulfate and 5 to 10 per cent of sodium sulfate and at a temperature between 10 and 90 C. The xanthate 45 threads, which may be guided over stretching rods, rollers, eyes or like stretching devices, are then taken by draft rollers and led to the fluted rollers. These latter, after they have imparted 50 the curliness, bring the material to the cutting machine, for instance that described in U. S. Patent No. 1,909,235. Then the xanthate threads are decomposed as described in the copending application Ser. No. 52,201 filed by 55 Zetzsche and Faber Nov. 29. 1935, in a glycol bath at a temperature of above 100 C.

What we claim is:

l. A process of producing curled staple fibers from viscose which comprises spinning viscose into a precipitating bath in which the viscose is decomposed only to cellulose xanthate, subject-- ing the xanthate threads to a-mechanical curle ing operation, decomposing the xanthate threads to threads of cellulose hydrate and cutting the threads to staples.

. 2. A process of producing curled staple fibers from viscose which comprises spinning viscose into a precipitating bath in which the viscose is decomposed only to cellulose xanthate, subjecting the xanthate threads to a treatment on fluted rollers, decomposing the xanthate threadsto threads of cellulose hydrate and cutting the threads to staples.

3. A process of producing curled staple fibers from viscose which comprises spinning viscose made from ripened alkali cellulose and containing 7 to 8 per cent of cellulose and 5 to 7 per cent of alkali through nozzles being provided with 600 to 1200 holes having a diameter of 0.08

mm. into a precipitating bath containing 25 per cent of ammonium suliate and 5 to 10 per cent of sodium sulfate at a temperature of 10 to 90 0., subjecting the xanthate threads to a treatment on fluted rollers, decomposing the xanthate threads to threads of cellulose hydrate and cutting the threads to staples.

4. A process of producing curled staple fibers from viscose including the step of cutting the threads to staples which comprises spinning viscose into a precipitating bath in which the viscose is decomposed only to cellulose xanthate, subjecting the xanthate threads to a mechanical curling operation and decomposing the threads to threads of cellulose hydrate.

5. A process of producing curled staple fibers from viscose which comprises spinning viscose into a precipitating bath in which the viscose is decomposed only to cellulose xanthate, subjecting the xanthate threads to a mechanical curling operation, cutting the threads to staples and decomposing the cut threads to threads oi cellulose hydrate.

WALTHER ZETZSCHE.

ERICK GRAUMANN. 

